Hi aminaak ,
Thanks for reaching out to us!
Our WhatsApp button actions uses the official WhatsApp URL. The URL will try to open the WhatsApp app if it installed on the device. If it fails to open the app, it will ask the user to download the app instead.
There are a couple of reasons as to why it might not be opening for the users.
Browser settings. There are browsers that have settings to prevent opening apps through links. Some prevent this by default and others prevent it when using incognito mode on the browser.
Some browsers could have a separate button like "Open in app" to give the control to the user.
Phone settings. There are also settings of the phone itself to also stop an app to open through links.
On Android, it is "Open supported links".
Hopefully this explains the situation a bit. Let us know if you have any further questions. 😄
